Electrical precipitating apparatus



June 24, 1930 ARRAS 1,767,338

ELECTRICAL PRECIPITATING APPARATUS Filed May 5, 1928 INVENTOR. Adamfir'r'ds A TTORNEYS.

Patented June 24, 1930 UNITED STATES PATENT OFFICE ADAM AREAS, OFFRANKFURT, GERMANY, ASSIGNOR TO INTERNATIONAL PRECIPITA- TION COMPANY,OF LOS ANGELES, CALIFORNIA, A CORPORATION OF CALIFORNIA ELECTRICALPRECIPITATING APPARATUS Application filed May 3, 1928 Serial No.

This invention relates to apparatus for electrical precipitation ofsuspended particles from gases, and particularly to electricalprecipitators of the type in which the collecting electrodes areprovided with hollow spaces and the collecting surfaces are providedwith openings leading into such hollow spaces and with baflles forassisting in collecting the precipitated material and directing the sameinto such hollow spaces.

One difiiculty which may sometimes occur with such electrodes is thatthe precipitated material chokes up at the openings leading into thehollow space and the collecting electrodes, due apparently to creationof a gas cushion or zone of increased pressure at these points, as aresult of which further precipitated material is prevented from enteringsaid hollow spaces and may be again carried away by the gas stream. Theprincipal object of this invention is to overcome this difiiculty,

which is accomplished by placing the hollow spaces or interior chambersof the collecting electrodes under a moderate or slight suction orreduced pressure, which need be only sufficient to prevent formation ofgas cushions or regions of increased pressure in said openings, thuspermitting free entrance of precipitated material therethrough.

The particular construction used for this purpose may be subject togreat variation, but one form of electrical precipitating apparatusembodying the above feature is shown in the accompanying drawings, inwhich:

Fig. 1 is asuch apparatus.

Fig. 2 is a partly sectional side elevation thereof.

Fig. 3 is an enlarged side elevation of a part of one of the collectingelectrodes, partly broken away.

Fig. 4 is a section on line 4- 1 in Fig. 8.

The electrical precipitator shown in the drawings comprises a casing orhousing 1 which may be of concrete construction as shown or may beconstructed of any other suitable material. An inlet flue 2 isrconnectedto one end of said housing and an outlet fiue 3 to the other end so asto provide for passage therethrough of the gas containing the partlysectional plan view of.

274,929, and in- Germany May 27, 1927.

suspended material to be precipitated. The interior of said housingconstitutes the main precipitating chamber, and within said chamber aremounted a plurality of collecting elec trode members 4:, supported forexample by means of bars 5. Each of said collecting electrodes is ofbox-like construction and is provided with two side walls or plates 4and is closed at the top as indicated at 6 and at the ends as indicatedat 7, so as to enclose a chamber 11 separate from the precipitatingchamber. The bottomof each electrode, however, is open as shown at 9, soas to permit material collected therein to fall into hopper 8 whichextends beneath the collecting electrodes, whence such material may beremoved in any suitable manner.

Each side plate 4: is provided with openings 10 distributed over thesurface thereof and leading into the hollow chamber 11 of the electrode.The direction of gas flow is indicated by the arrows A in Figs. 1 and 4,and battle members 12 are provided just beyond each opening 10 in thedirection of gas flow so as to cause any material precipitated on theside walls 4 and tending to move along the surface of such side Wallsdue to the friction of the moving gas stream thereupon, to pass throughsaid opening and into the chamber 11. Such openings and battle means mayadvantageously be formed by making a plurality of V-shaped cuts atproper intervals on each side plate 4 and outwardly bending or deformingthe metal between the two sides of each cut, as shown in Figs. 3 and 4.

According to the present invention suitable means are provided formaintaining within the chamber 11 of each collecting electrode a suctionorreduced pressure, that is to say, a pressure less than that existingin the precipitating apparatus and outside the collecting electrodes.For this purpose pipes 15 provided with openings 16 may extendthroughout the length of the collecting electrodes and near the upperend of the hollow chambers 11 thereof. Said pipes may extend downwardlyas at 17 at one end of the precipitato r, entering a header or manifold18 connected to the inlet 19 of a fan or exhauster 20-, driven forexample by electric motor 21.

The outlet 22 of said fan or exhauster may lead to any suitable point,but in order to provide for collection in the same precipitatingapparatus of any suspended material removed with the gas through pipes15, said outlet preferably communicates with the precipitator inlet flue2 as shown at 23.

Suitable discharge electrode means such as wires or the like indicatedat 25 are provided between the respective collecting electrodes, saiddischarge electrodes being hung from bars 26 supported by means of framemembers 27 on insulating supports 28. The spacing of the individualdischarge electrode members from one another, as well as the spacing ofsaid members from the opposing side plates 4 of the collectingelectrodes, may conform substantially to the usual practice inelectrical precipitating apparatus. Any suitable means may be providedfor maintaining the necessary high potential difference between thedischarge and collecting electrodes. For example, the collectingelectrodes may be grounded as indicated at 30 and the dischargeelectrode system may be connected as by wire 31 to one side of asuitable sourceof high tension electric current, preferably rectifiedalternating current, the other side of said source being also groundedto complete the circuit. The spaces within the housing 1, and

outside of and between the collecting elec trodes, may be considered ascomprising the precipitating chamber or chambers of the.

apparatus.

In the operation of the above described apparatus, with the electriccircuit established, the suspended material contained in the gas passingbetween the discharge and collecting electrodes will become electricallycharged and will be precipitated wholly or partially upon the side walls4 of the collecting electrodes and, due to the drag of the gas thereon,such precipitated material will move along the surfaces of such sidewalls and pass through openings 10 into the hollow spaces or chamber 11of the collecting electrodes. With the fan or exhauster 20 in operation,gas will be continually withdrawn from the chambers 11 so as to maintaintherein a pressure slightly less than that outside said chambers andthus cause a continual slight flow of gas through openings 10. This willnot only prevent the creation of gas cushions or regions of increasedressure in these openings, which have hereto ore tended to prevent freepassage of precipitated material therethrough but may also actuallypromote thefpassage of such material through said openings byentrainment with the gas.

The precipitated material thus entering the chambers 11 falls, for thegreater part, through the open bottoms of said chambers into hoppers 8,while the gas passes through pipes 17,18 and 19 to fan 20 and hencethrough pipe 22 back to the main gas stream entering the precipitator,Any solid'material carried out of the chambers 11 in suspension in thiscirculating gas will, therefore, not be lost or permitted to escape, butwill be again precipitated and collected in the electrical precipitator.It will be understood, of course, that the amount of gas drawn inthrough openings 10 and returned through pipe 22 is relatively small ascompared to the total amount of gas passing through the precipitator, sothat the return of such gas to the inlet flue does not greatly increasethe velocity of gas in theprecipitator nor does the relatively smallquantity of suspended material returned with such circulated gasmateriallv increase the amount of material to be precipitated.

I claim:

1. In an electrical precipitating apparatus, a collecting electrodehaving an interior chamber and provided with opening means leading intosaid chamber and battles cooperating with said opening means to directprecipitated material into said chamber, and means for maintainingwithin said chamber a pressure less than that in the precipitator andoutside said chamber.

2. In an electrical precipitating apparatus, a collecting electrodehaving an interior chamber and provided with opening means leading intosaid chamber and with baflie chamber, a collecting electrode mounted insaid precipitator chamber and having a chamber separate from the mainprecipitating chamber and provided with opening means leading from saidprecipitator chamber into said separate chamber, means for maintainingwithin said separate chamber a pressure less than that in theprecipitator chamber so as to cause gas from the preci itator chamber,together with precipitate material, to pass through said openin meansinto said separate chamber; means %or collecting precipitated materialentering said separate chamber, and means for returnin said gas, afterremoval of such precipitate material, to the precipitator chamber.

5. An electrical precipitating apparatus comprising housing meansenclosing a precipitator chamber and provided with means for supplyinggas contaming suspended particles to said precipitator chain er and forremoving gas from said precipitator chamber, a collecting electrode andopposing discharge electrode means disposed within said precipitatorchamber, means for maintaining a difierence of potential between saidcollecting electrode and said discharge electrode means, said collectingelectrode having a chamber separate from the recipitator chamber andbeing provided w1th opening means distributed over the collectingsurface thereof and leading from said precipitator chamber into saidseparate chamber, means for maintaining within said separate chamber apressure less than that in the precipitator chamber so as to cause aportion of the gas in said precipitator chamber adjacent said collectingelectrode topass together with precipitated material through saidopening means into said separate chamber, means for collectingprecipitated material entering said separate chamber, and means forreturning said gas, after separation of such precipitated material, tosaid precipitator chamber.

In testimony whereof I have hereunto subscribed my name this 11th day ofApril, 1928.

ADAM ARRA'S.

